Fuse



A. Y. LEECH, JR, ETAL FUSE Filed Sept. 1 1942 2,] wu We, 3% $22209. k

Patented Aug. 13, 1946 FUSE Abner Y. Leech, Jr., and Henry H. Mohaupt,

Washington, D. C., assignors to Societe Anonyme de Gestion et Dexploitation dc Brevets,

Switzerland Application September 1, 1942, Serial No. 456,919 8 Claims. (01. 102 -78) This invention relates to impact fuses especially suitable for use in bombs dropped from planes against submarines but is applicable to use in projectiles for certain purposes.

In order more fully to understand and appreciate the present invention, it may be explained that bombs carried by aeroplanes must be absolutely safe at all times until actually dropped and should remain so to prevent explosion even should the plane be forced down at sea. The bombs must be able to withstand very severe dropping and bumping tests without premature detonation. This is especially true for bombs used b carrierbased aeroplanes which may land on deck under adverse conditions and with great shock.

A bomb exploding a short distance from a submerged submarine may do little more than shake up the crew. Consequently, hydrostatic pressure or time-actuated fuses are of little use in actually combatting modern submarines which submerge before the actual moment of attack and may be far below the surface. Due to the perfecting of aeroplane listening devices carried by submarines, it is rarely that a submarine is actually attacked by aeroplane while on the surface. On first sign of an attacking plane, the submarine makes a crash dive and is under water by the time the aeroplane actually reaches the scene of attack, but often is not out of sight from the aeroplane overhead.

The present invention deals with an impact fuse ideally suited for just such conditions and work; namely, drop bombs which are adapted to be salvoed over the submerged submarine and which will automatically arm only on striking the surface of the water and explode only on striking a second surface or a solid object beneath the water. It is obvious that such a construction is especially suited for this specialized use because of the safety feature which permits detonation only when the target is hit regardless of the depth the submarine may be submerged. It will not eX- plode on a crash of the carrying plane, at sea, land, or on deck.

It is accordingly one of the main objects of the invention to provide a reliable and eflicient fuse of the above character which will be absolutely safe at all times prior to actual impact with water after the bomb is launched or dropped.

A further object is to provide a fuse of the above character which will be instantly conditioned only on impact with a first surface such as water as distinguished from arming by pull wires. spinners, hydrostatic pressure or time elements, and which will explode the charge only on impact with a second surface, that is a submerged solid object irrespective of the depth of submerence.

A further object is to provide a fuse having relatively few parts which may be inexpensively manufactured and assembled.

A further object is to provide a fuse which will be safe to handle either directly or indirectly at all times.

A further object is to provide a fuse which will be certain in its operation only under circumstances as above set forth.

Other objects will be in part obvious from the annexed drawing and in part hereinafter indicated in connection therewith by the following analysis of the invention.

This invention accordingly consists in the features of construction, combination of parts and in the unique relation of the members and in the relative proportioning and disposition thereof, all as more completely outlined herein.

To enable others skilled in the art fully to comprehend the underlying features of this invention, that they may embody the same by the numerous modifications in structure and relation contemplated by the invention, a drawing depicting several forms of the invention has been annexed as part of thi disclosure, and in such drawing like characters of reference denote corresponding parts throughout all of the views, in which- Figs. 1 and 2 are longitudinal elevational views of one form of fuse showing the parts in normal safe position and armed position, respectively;

Fig. 3 is a similar view showing a modified form of fuse in safe position; and

Fig. 4 is a similar view showing a further modified form of fuse in safe position.

Referring now to the drawing in detail, and more particularly to Fig. 1, 10 indicates the body member of the fuse which is of general cylindrical shape adapted to be screwed into the base of the drop bomb in the usual well known manner. The body member has a depending tube I l and is provided with a through bore l2 adapted to be closed by a screw plug [3 at the upper part and a detonator carrying plug M at the lower part. Within this closed tubular bore H is positioned the firing mechanism for the detonator.

Referring first to the detonator carrying plug Hi, there is provided an open chamber for receiving a booster l5 and a passage [6 at the upper end is sealed by a transversely movable safety block ll carrying a detonator l8 which is normally out of line with the firing pin 20 and the booster I5. This detonator safety block H is held in its normal position against lateral movement by means of a locking device 2| held in its raised position, as shown, by any suitable means such as a small shear pin 22. On the moment of impact, however, with the surface water, the pin 22 i sheared and the mass 2| moves downwardly to carry a detent 23 out of a recess 24 in the detonator carrying member H. The instant the impact or inertia member 2| moves downwardly, then a small coiled spring 25 which is under compression, instantly forces the detonator carrying member I! towards the left, thereby bringing the detonator l8 into line with the firing pin 26 so that when the firing pin is subsequently released on contact with a second surface or target impact, the train of explosives |8|5 is ignited to the usual bursting charge of conventional type carried by the bomb, but not herein shown.

Immediately above the detonating mechanism i positioned a cup-like cylindrical part 23 carry-'- ing the firing pin 20, and this is locked in position by means of balls 21 engaging recesses in the cup 26 and an annular groove in the tubular portion II of the fuse body. These balls 21 are held in looking position by means of a plunger 28 normally held in the position shown in Fig. 1 by means of a coiled spring 30. The plunger member is provided with an upwardly extending stem 3| upon which is mounted a momentum member 32 which is free to slide downwardly 0n the stem against the action of spring 33 on the instant of water impact, thereby to assume the position shown in Fig. 2 and hold the spring 33 in compressed condition as shown.

This member 32 which may also be termed an abutment member, is locked in its lower position shown in Fig. 2 by any suitable means such, for example, as a spring catch 34 housed in a suitable opening or recess 35 in the side of th tubular portion ll of the fuse body.

The plunger 28, however, and the coacting firing pin 20 are still retained locked in the position shown in Fig. 1 by means of a ball locking device 33 engaging a recessed or grooved member 36 permanently secured to the top of the stem 3|. The ball 39, as herein shown, is partially in a recess 3! in the fuse body and partially in the recess of the member 36 and is locked in position by means of a momentum actuating part 33 housed in a separate air cushion bore 45 at one side of the fuse body ID.

If desired, a small shear pin 4|, or the like, may be employed to prevent any longitudinal movement of this part 38 up to the moment of water impact. It will be noted, however, that this member 38 has a downwardly extending portion 42 free to move in a recess 43 in the lower part of the fuse body l5 and against the action of a partially compressed coil spring 44. The upper end of this bore is closed by a screw plug 45 for the purpose of protecting the movable parts.

By reference to Fig. 2 it will be seen that on the moment of impact with the water, the part 38 moves first downwardly against the action of spring M and continues to hold the ball 3! in its locking position, but as soon as the effect of the first impact is over, then the part 38 is forced upwardly by the spring 34 allowing the ball 39 to roll out of engagement with the groove in the member 35 and into the position shown in Fig. Thereafter, on target impact, a hammer member 56 is free to slide downwardly by reason of it's arrested momentum and carry with it the recessed,

locking plate 35, the stem 3| and plunger 28, thereby instantly releasing the balls 21 from their engagement with the groove in the interior wall of the tubular portion II of the fuse body, but the cup 23 and plunger 28 remain locked together. Thereupon the spring 33 being under high compression, as shown in Fig. 2, is free to force the cup member 25 carrying the firing pin 23 downwardly to engage the detonator l8 and fire chain of explosives to the main charge.

The operation of this device is substantially as follows: Assuming the parts to be in safe, unarmed position, as shown in Fig. 1, the bomb is launched or dropped and on the instant of impact with water the various movable parts instantly and simultaneously function to arm the bomb, that is, the member 2| moves downwardly to release the detonator carrying member H which is instantly forced towards the left by the compressed spring 25 thereby bringing the detonator l8 in line with the booster l5. Simultaneously the inertia member 32 moves downwardly to compress the spiral spring 33 and becomes locked by means of the latch 34 in the position shown in Fig. 2. Also simultaneously with the movement of these parts the inertia member 33 is forced downwardly against the action of spring 2-4 but this movement still holds the locking ball 39 in engagement with the recess in the member 36' whereby movement of the firing pin release mechanism is prevented. However, immediately after the instant of water impact, the inertia member 38 is forced upwardly to the position shown in Fig. 2, allowing the locking ball 39 to roll down the inclined wall of the reces in part Ill into the position shown in Fig. 2 whereupon the hammer member 46 is free to move on the instant of target impact, that is, the deck of the submarine which may be any distance beneath the surface of the water. When the target is contacted, the entire movement of the bomb is arrested and the hammer member 43 immediately moves downwardly by reason of its momentum, thereby carrying the part 36 and the stem 3| to instantly release the locking balls 2'! from their coactive engagement with the wall of the fuse body and the compressed spring 33 functions to forcibly drive the firing pin 23 into engagement with the detonator and explode the bomb.

The mechanism shown in Fig. 3 is very similar to that above described, that is, the lower part of thev fuse body 50 is closed by a detonator carrying plug exactly the same as shown in Fig. l and it is unnecessary to describe that part again. Likewise the means for holding the cup 5| is the same, except that instead of having the firing pin integrally formed with the cup, a separate firing pin 52 is mounted upon the lower end of the lock release member 53 and at the lower end of stem 54 upon which a similar inertia member 55 is free to slide. Between the cup 5| and inertia member 55 is positioned a coiled spring 56 which is compressed on the downward movement of the inertia member 55 on the first impact and this member is locked in its lower position with the spring compressed by a similar detent 51.

The upper end of the stem 54,-however, carries various locking and safety devices, all of which constitute the hammer member which functions on target impact to drive the firing pin 52 forcibly into engagement with the detonator I3. This hammer member comprises a general cylindrical block 58 provided with two vertically disposed bores 60 and 6| and a single transverse bore 62 each of which is provided with a slidable memher, 63, 64 and 65 respectively. Considering first the bore and inertia member 63, the latter is provided with a shear pin 66 or the like for holding the same in normal position. However, on the moment of water impact the shear pin 66 is broken and the inertia member 63 moves relatively downwardly to bring the groove 61 opposite a locking ball 68 into the fixed partition wall 10. Until this happens, however, the inertia member 64 is positively held against movement, but by the time that the efiect of water impact is over, the ball 68 is moved downwardly towards the right into the groove 51 allowing the second movable member 64 to move upwardly under the action of the compressed spring 1|. This movement, of course, carries the stem 12 upwardly, thereby relieving the laterally movable member which is instantly forced relatively towards the left by spring I3, carrying with it the extreme right hand end I4 fitting within a suitable recess in the side wall of the body member 58, thus completely releasing the hammer member whereby it is free to move downwardly on target impact to drive the firing pin into engagement with the detonator.

The three movements of the parts 63, 54 and 65 occur almost instantaneously, yet there is a sufiicient delay due to air cushion in bore 6| to prevent any movement of the hammer member 58 on water impact yet will permit the bomb to obtain normal sinking speed which kills inertia and then allows the hammer to move on target impact immediately thereafter.

The point of th firing pin 52 is normally screened from the detonator by being locked in the position shown by the device above described. The cup 5| is held in position by balls 13 seated partly in recesses in the fuse body 58 and partly in openings in the cup 5| and are held by the part '53. On impact with the second surface the hammer moves downwardly by its inertia and weight to lower the parts 53, thus allowin the balls 13 to move out from the recesses in the fuse body, whereupon the balls jam below the top surface of part 53 and the tops of the recesses in cup 5| and lock these parts together, whereupon the spring 55 under compression expands to drive the cup and pin and these with the hammer cause the desired detonation.

The operation of this mechanism is broadly almost identical to the operation of the modification shown in Fig. 1 and it is unnecessary to further comment on the same. It must be noted, however, that the parts 5| and 53 are locked together on target impact and the spring 55 augments the action of inertia.

In Fig. 4 a further modification is shown, it being understood that the lower part of this fuse may be either of the type shown in Figs. 1 and 2 or in Fig. 3. In this view the fuse casing 50 is the same as previously described, together with the firing pin stem 54 and inertia member 55 and spring 56. The safety device, however, is somewhat different. Here a cylindrical hammer 88 with self-contained safety devices is adapted to slide in the fuse body 50 and is normallylocked in the position shown by means of a laterally movable member 8| having a vertical bore 82 in line with a locking pin 83. This member 8| has positioned between the shoulder on the hammer and a shoulder 84 a normally compressed spring 85. The locking pin 83 has a shoulder engaging the recess 86 and is held in this position by means of a laterally movable pin 8| having a bore 82 in line with a locking stem 83.

This plunger or member 8| has positioned between the shoulder on the hammer 88 and a shoulder 84 a compressed spring 85. The looking pin 83 has a shoulder engaging the recess 86 and is held in this position by means of a wateractuated cup 81' or spinner, if desired. The cup is shown with the outwardly flaring skirt portion which is adapted to be engaged by the water as it hits the surface, thereby to raise the stem 83 and release its lower engagement with the bore 82. A packing ring 88 prevents leakage of water after the bomb is submerged, for obviously if the bomb should sink a hundred feet or more before it hits its target or second surface of impact the water pressure might permit a certain amount of water to pass into the fuse detonator. To further guard against this contingency the stem 83 is tapered as at 90 to coact with a similarly tapered watertight surface in nut 9| screwed into the top of the fuse plug.

At one side of the stem 83 is an inertia member 92 normally mounted in an almost airtight cup and held in raised position by means of spring 94. On the moment of first impact, this inertia member 82 movesdownwardly into a cavity 95 at one side of the member 8|, thus preventing any movement of the member 8| until after the effect of inertia on the part 92 has been eliminated. Immediately thereafter, however, the member 92 moves slowly back to the position shown because of the air cushion, whereupon the member 8| can move towards the left, pulling the bolt 85 out of the recess in the fuse body, thereby permitting the hammer an to move downwardly at the moment of second impact.

The complete operation of this entire mechanism is substantially the same as that above described in connection with Fig. 3, except that in this case a safety pin or other locking device 96 is preferably supplied to prevent accidental movement of the cup 81, thus insuring against accidental arming during handling and loading of the bomb. This pin is of course released when or before the bomb is dropped.

It will also be noted that the lower part 91 of the cup 81 should always be tight against the top of the fuse body for, if it is not, then the lower end of the stem 83 may have been withdrawn from the bore 82 and the safety device eliminated, which of course would cause the bomb to explode on contact with the first surface.

All of these devices, it will be seen, are particularly suitable for accomplishing the objects and results set forth in the opening paragraphs in a reliable and effective manner. The fuses are, as above explained, particularly suitable for combatting submarines in accordance with the new technique necessitated by present war conditions. It frequently happens that a submarine on the surface is cited by an aeroplane almost simultaneously with the discovery of the aeroplane by observers on the submarine and if a crash dive is ordered, it can rarely be consummated before the aeroplane has arrived in the vicinity of the submarine and in a position to attack by launching the bombs. If the submarine is only a few feet below the surface, the bombs will function by becoming armed on water impact and detonated on target impact and should the submarine still be on the surface, the weight of the bomb will be sufficient to penetrate the deck and to this extent arm the bomb shown in Fig. 3, which is analogous to the water impact feature above described; and when the bomb is finally arrested by a lower deck or surface in the interior 7 of the submarine, then the effect is the same as target impact and the bomb will explode. The fuse shown in Fig. 3 is especially applicable to either bombs or projectiles and would be very effective whereit is desired to arm the fuse on impact with armor and explode on hitting any second surface thereafter.

It is thus seen that the present invention provides a fuse ideally designed for accomplishing the particular objects and advantages herein set forth.

As; many changes could, be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

We claim: 1. A fuse for drop bombs of the character described comprising, in combination, a fuse body having a main through bore, closure means at each end of said bore, a detonator in one of said closure means, safety means normally holding the detonator in safe position, ,a member having a firing pin normally spaced from said detonator, means for locking the firing pin against movement until target impact, a movable abutment member, a spring between said two last members adapted to be compressed on water impact, a locking means for holding the abutment member in its moved position with the spring in compressed condition, a hammer in said bore and free to move only on target impact, a locking means for said hammer, and means holding the hammer in looking position until after water impact whereupon the hammer member is free to move the firing pin on target impact. 2. A fuse for drop bombs of the character described comprising, in combination, a fuse body having a main through bore, closure means at each end of said bore, a detonator in safe outof-line position, a member having a firing pin normally spaced from said detonator and in line therewith only when said detonator is in armed position, means for locking the firing pin against movement until target impact, a movable abutment member, a spring between said two last members adapted to be compressed on water impact, a locking means for holding the abutment member in its moved position with the spring in compressed condition, a hammer in said bore and free to move only on target impact, a locking means for said hammer, and means holding the hammer in locking position until after water impact whereupon the hammer memher is free to move the firing pin on target impact.

3. A base fuse for drop bombs of the character described comprising, in combination, a fuse body having a main through bore, closure plugs at each end of said bore, a detonator in one of said plugs, safety means in said plug normally holding the detonator in safe position, means to arm the fuse at the moment of water impact, a firing pin for the detonator operative only when the detonator is in armed position, means for locking the firing pin against movement until target impact including a movable member having a stem actuated on target impact to release the locking means, an abutment member slidable on said stem, a spring adapted to be compressed on water impact, a locking means for holding the abutment member in its moved position with the spring in compressed condition, a hammer in the upper part of the bore, a locking means for said hammer including a recessed member mounted onthe upper end of said stem, locking means coacting with the recess and fuse body, and a spring-conditioned member free to move the firing pin on target impact.

4. A base fuse for drop bombs of the character described comprising, in combination, a fuse body adapted to be secured in the base of a bomb and having a main through bore, closure plugs at each end of said bore, a detonator in one of said plugs, safety means in said plug normally holding the detonator in safe condition, a cup-like member having a firing pin normally spacedfrom said detonator, means for locking the firing pin against movement until target impact, a movable abutment member adapted to move forward on water impact, a spring adapted to be'compressed thereby on water impact, a locking means for holding the abutment member in its forward moved position with the spring in compressed condition, a hammer free to move only on target impact, a locking means for said hammer, and a spring controlled member for releasing the hammer upon target impact.

5. A base fuse for drop bombs of the character described comprising, in combination, a fuse body adapted to be secured in the base of a bomb of general cylindrical shape and having a main through bore, closure plugs at each end of said bore, a detonator in one of said plugs, safety means normally holding the detonator in safe position including a water impact actuated device and spring means for moving said detonator to armed position at the moment of water impact, a cup-like member, a firing pin associated therewith normally spaced from said detonator, means for locking the firing pin against movement until target impact including locking balls coacting with the fuse body and cup and a movable memher having a stem actuated on target impact to release the locking balls, an abutment member slidable on said stem, a spring between said last member and cup adapted to be compressed on water impact, a locking means for holding the spring in compressed condition, a hammer free to move only on target impact, a locking means for said hammer including a member mounted on the upper end of said stem, locking means coacting with the fuse body, and a releasable springconditioned member holding the hammer member free to move the firing pin on target impact.

6. A fuse for drop bombs of the character described comprising, in combination, a fuse body having a main through bore, closure means at each end of said bore, a detonator in one of said means, a safety device in one of said means normally holding the detonator in safe position including a water impact actuated device and means for arming said detonator at the moment of water impact, a member having a firing pin positioned to engage with said detonator only in armed position, means normally locking the firing pin against movement until target impact and then to release the locking means, a slidable inertia member, a spring adapted to be compressed on water impact, a locking means for holding the inertia member in its moved position, a hammer in the upper part of the bore and free to move only on target impact, a locking means for said hammer holding the same until water impact whereby the hammer member is free to move the firing pin on target impact.

7. A fuse for drop bombs of the character described comprising, in combination, a fuse body of general cylindrical shape and having a main through bore, closure plugs for said bore, a detonator in one of said plugs, safety means normally holding the detonator in safe position including a water impact actuated device for relatively moving said detonator at the moment of water impact, a firing pin normally spaced from said detonator and in line therewith only when said detonate-r is in armed position, means for locking the firing pin until target impact including locking balls and a movable member having a stem actuated on target impact to release the locking balls, an abutment member slidable on said stem, a spring between said last member and cup adapted to be compressed on water impact, a locking means for holding the spring in compressed condition, a hammer free to move only on target impact, a locking means for said hammer, and a spring-conditioned member holding the locking means in position until water impact whereby the hammer member is then free to release the trigger moving the firing pin on target impact.

8. A base fuse for drop bombs of the character described comprising, in combination, a fuse body of general cylindrical shape adapted to be secured in the base of a bomb and having a main through bore, closure plugs at each end of said bore, a detonator and primer in one of said plugs, safety 10 means in said plug normally holding the detonator in safe position including a water impact actuated device and spring means for moving said detonator to armed position at the moment of water impact, a cup-like member having a firing pin normally spaced from said detonator and in line therewith only when said detonator is in armed position, means for locking the firing pin against movement until target impact including locking balls coacting with the fuse body and cup and a movable member having a stem actuated on target impact to release the locking balls, an abutment member slidable on said stem, a sprin between said last member and cup adapted to be compressed on water impact, a locking detent for holding the abutment member in its moved position with the spring in compressed condition, a hammer in the upper part of the bore and free to move only on target impact, a locking means for said hammer including a recessed member mounted on the upper end of said stem, locking balls coacting with the recess and fuse body, and a spring-conditioned member holding the balls in looking position until water impact whereby the hammer member is free to move the firing pin on target impact.

ABNER Y. LEECH, JR.

HENRY H. MOHAUPT. 

